Semiconductor device and manufacturing method thereof

Abstract

In order to increase an aperture ratio, a part of or all of a gate electrode that overlaps with channel formation regions ( 213, 214 ) of a pixel TFT is caused to overlap with second wirings (source line or drain line) ( 154, 157 ). Additionally, a first interlayer insulating film ( 149 ) and a second interlayer insulating film ( 150 c ) are disposed between the gate electrode and the second wirings ( 154, 157 ) so as to decrease a parasitic capacitance.

1. A method for manufacturing a semiconductor device comprising:
 forming a crystalline semiconductor layer on an insulating surface, wherein the crystalline semiconductor layer includes a source region, a drain region and a channel formation region; 
 forming a gate insulating film over the crystalline semiconductor layer; 
 forming a first interlayer insulating film over the gate insulating film; 
 forming a second interlayer insulating film over the first interlayer insulating film; 
 etching a portion of the second interlayer insulating film by a wet-etching, thereby eliminating the second interlayer insulating film disposed over the source region or the drain region; 
 etching the first interlayer insulating film and the gate insulating film to form a contact hole which reaches at least one of the source region and the drain region, wherein at least one of the source region and the drain region is also etched; and 
 forming a pixel electrode electrically connected to one of the source region and the drain region, 
 wherein a selective etching ratio of the first interlayer insulating film to the crystalline semiconductor layer is from 12 to 15. 
 
   
   
     2. A method for manufacturing a semiconductor device according to  claim 1 , wherein the first interlayer insulating film contains silicon oxide. 
   
   
     3. A method for manufacturing a semiconductor device according to  claim 1 , wherein the source region or the drain region has a thickness from 10 to 50 nm. 
   
   
     4. A method for manufacturing a semiconductor device according to  claim 1 , wherein the semiconductor device is at least one selected from the group consisting of a personal computer, a video camera, a digital camera, a mobile computer, a player that uses a recording medium, a portable telephone, and an electronic book. 
   
   
     5. A method for manufacturing a semiconductor device according to  claim 1 , wherein a diameter of the contact hole is 1 μm or less. 
   
   
     6. A method for manufacturing a semiconductor device according to  claim 1 , wherein an etching amount of the at least one of the source region and the drain region is less than 5 nm. 
   
   
     7. A method for manufacturing a semiconductor device comprising:
 forming a crystalline semiconductor layer on an insulating surface, wherein the crystalline semiconductor layer includes a source region, a drain region and a channel formation region; 
 forming a gate insulating film over the crystalline semiconductor layer; 
 forming a first interlayer insulating film over the gate insulating film; 
 forming a second interlayer insulating film over the first interlayer insulating film; 
 etching a portion of the second interlayer insulating film by a wet-etching, thereby eliminating the second interlayer insulating film disposed over the source region or the drain region; and and 
 etching the first interlayer insulating film and the gate insulating film to form a contact hole which reaches at least one of the source region and the drain region, wherein at least one of the source region and the drain region is also etched, 
 wherein a selective etching ratio of the first interlayer insulating film to the crystalline semiconductor layer is from 12 to 15. 
 
   
   
     8. A method for manufacturing a semiconductor device according to  claim 7 , wherein the first interlayer insulating film contains silicon oxide. 
   
   
     9. A method for manufacturing a semiconductor device according to  claim 7 , wherein the source region or the drain region has a thickness from 10 to 50 nm. 
   
   
     10. A method for manufacturing a semiconductor device according to  claim 7 , wherein the semiconductor device is at least one selected from the group consisting of a personal computer, a video camera, a digital camera, a mobile computer, a player that uses a recording medium, a portable telephone, and an electronic book. 
   
   
     11. A method for manufacturing a semiconductor device according to  claim 7 , wherein a diameter of the contact hole is 1 μm or less. 
   
   
     12. A method for manufacturing a semiconductor device according to  claim 7 , wherein an etching amount of the at least one of the source region and the drain region is less than 5 nm. 
   
   
     13. A method for manufacturing a semiconductor device comprising:
 forming a crystalline semiconductor layer on an insulating surface, wherein the crystalline semiconductor layer includes a source region, a drain region and a channel formation region; 
 forming a gate insulating film over the crystalline semiconductor layer; 
 forming a first interlayer insulating film over the gate insulating film; 
 forming a second interlayer insulating film over the first interlayer insulating film; 
 etching a portion of the second interlayer insulating film by a wet-etching, thereby eliminating the second interlayer insulating film disposed over the source region or the drain region; 
 etching the first interlayer insulating film and the gate insulating film to form a contact hole which reaches at least one of the source region and the drain region by a dry etching, wherein at least one of the source region and the drain region is also etched; and 
 forming a pixel electrode electrically connected to one of the source region and the drain region, 
 wherein a selective etching ratio of the first interlayer insulating film to the crystalline semiconductor layer is from 12 to 15. 
 
   
   
     14. A method for manufacturing a semiconductor device according to  claim 13 , wherein the first interlayer insulating film contains silicon oxide. 
   
   
     15. A method for manufacturing a semiconductor device according to  claim 13 , wherein the source region or the drain region has a thickness from 10 to 50 nm. 
   
   
     16. A method for manufacturing a semiconductor device according to  claim 13 , wherein the semiconductor device is at least one selected from the group consisting of a personal computer, a video camera, a digital camera, a mobile computer, a player that uses a recording medium, a portable telephone, and an electronic book. 
   
   
     17. A method for manufacturing a semiconductor device according to  claim 13 , wherein a diameter of the contact hole is 1 μm or less. 
   
   
     18. A method for manufacturing a semiconductor device according to  claim 13 , wherein an etching amount of the at least one of the source region and the drain region is less than 5 nm. 
   
   
     19. A method for manufacturing a semiconductor device comprising:
 forming a crystalline semiconductor layer on an insulating surface, wherein the crystalline semiconductor layer includes a source region, a drain region and a channel formation region; 
 forming a gate insulating film over the crystalline semiconductor layer; 
 forming a first interlayer insulating film over the gate insulating film; 
 forming a second interlayer insulating film over the first interlayer insulating film; 
 etching a portion of the second interlayer insulating film by a wet-etching, thereby eliminating the second interlayer insulating film disposed over the source region or the drain region; 
 etching the first interlayer insulating film and the gate insulating film to form a contact hole which reaches at least one of the source region and the drain region, wherein at least one of the source region and the drain region is also etched; 
 forming a wiring electrically connected to the at least one of the source region and the drain region though the contact hole; and 
 forming a pixel electrode electrically connected to the wiring, 
 wherein a selective etching ratio of the first interlayer insulating film to the crystalline semiconductor layer is from 12 to 15. 
 
   
   
     20. A method for manufacturing a semiconductor device according to  claim 19 , wherein the first interlayer insulating film contains silicon oxide. 
   
   
     21. A method for manufacturing a semiconductor device according to  claim 19 , wherein the source region or the drain region has a thickness from 10 to 50 nm. 
   
   
     22. A method for manufacturing a semiconductor device according to  claim 19 , wherein the semiconductor device is at least one selected from the group consisting of a personal computer, a video camera, a digital camera, a mobile computer, a player that uses a recording medium, a portable telephone, and an electronic book. 
   
   
     23. A method for manufacturing a semiconductor device according to  claim 19 , wherein a diameter of the contact hole is 1 μm or less. 
   
   
     24. A method for manufacturing a semiconductor device according to  claim 19 , wherein an etching amount of the at least one of the source region and the drain region is less than 5 nm. 
   
   
     25. A method for manufacturing a semiconductor device comprising:
 forming a crystalline semiconductor layer on an insulating surface, wherein the crystalline semiconductor layer includes a source region, a drain region and a channel formation region; 
 forming a gate insulating film over the crystalline semiconductor layer; 
 forming a first interlayer insulating film over the gate insulating film; 
 forming a second interlayer insulating film over the first interlayer insulating film; 
 etching a portion of the second interlayer insulating film by a wet-etching, thereby eliminating the second interlayer insulating film disposed over the source region or the drain region; 
 etching the first interlayer insulating film and the gate insulating film to form a contact hole which reaches at least one of the source region and the drain region, wherein at least one of the source region and the drain region is also etched; and 
 forming a wiring electrically connected to the at least one of the source region and the drain region through the contact hole, 
 wherein a selective etching ratio of the first interlayer insulating film to the crystalline semiconductor layer is from 12 to 15. 
 
   
   
     26. A method for manufacturing a semiconductor device according to  claim 25 , wherein the first interlayer insulating film contains silicon oxide. 
   
   
     27. A method for manufacturing a semiconductor device according to  claim 25 , wherein the source region or the drain region has a thickness from 10 to 50 nm. 
   
   
     28. A method for manufacturing a semiconductor device according to  claim 25 , wherein the semiconductor device is at least one selected from the group consisting of a personal computer, a video camera, a digital camera, a mobile computer, a player that uses a recording medium, a portable telephone, and an electronic book. 
   
   
     29. A method for manufacturing a semiconductor device according to  claim 25 , wherein a diameter of the contact hole is 1 μm or less. 
   
   
     30. A method for manufacturing a semiconductor device according to  claim 25 , wherein an etching amount of the at least one of the source region and the drain region is less than 5 nm. 
   
   
     31. A method for manufacturing a semiconductor device comprising:
 forming a crystalline semiconductor layer on an insulating surface, wherein the crystalline semiconductor layer includes a source region, a drain region and a channel formation region; 
 forming a gate insulating film over the crystalline semiconductor layer; 
 forming a first interlayer insulating film over the gate insulating film; 
 forming a second interlayer insulating film over the first interlayer insulating film; 
 etching a portion of the second interlayer insulating film by a wet-etching, thereby eliminating the second interlayer insulating film disposed over the source region or the drain region; and 
 etching the first interlayer insulating film and the gate insulating film to form a contact hole which reaches at least one of the source region and the drain region by a dry etching, wherein at least one of the source region and the drain region is also etched, 
 wherein a selective etching ratio of the first interlayer insulating film to the crystalline semiconductor layer is from 12 to 15. 
 
   
   
     32. A method for manufacturing a semiconductor device according to  claim 31 , wherein the first interlayer insulating film contains silicon oxide. 
   
   
     33. A method for manufacturing a semiconductor device according to  claim 31 , wherein the source region or the drain region has a thickness from 10 to 50 nm. 
   
   
     34. A method for manufacturing a semiconductor device according to  claim 31 , wherein the semiconductor device is at least one selected from the group consisting of a personal computer, a video camera, a digital camera, a mobile computer, a player that uses a recording medium, a portable telephone, and an electronic book. 
   
   
     35. A method for manufacturing a semiconductor device according to  claim 31 , wherein a diameter of the contact hole is 1 μm or less. 
   
   
     36. A method for manufacturing a semiconductor device according to  claim 31 , wherein an etching amount of the at least one of the source region and the drain region is less than 5 nm. 
   
   
     37. A method for manufacturing a semiconductor device comprising:
 forming a crystalline semiconductor layer on an insulating surface, wherein the crystalline semiconductor layer includes a source region, a drain region and a channel formation region; 
 forming a gate insulating film over the crystalline semiconductor layer; 
 forming a first interlayer insulating film over the gate insulating film; 
 forming a second interlayer insulating film over the first interlayer insulating film; 
 etching a portion of the second interlayer insulating film by a wet-etching, thereby eliminating the second interlayer insulating film disposed over the source region or the drain region; 
 etching the first interlayer insulating film and the gate insulating film to form a contact hole which reaches at least one of the source region and the drain region by a dry etching, wherein at least one of the source region and the drain region is also etched; and 
 forming a wiring electrically connected to the at least one of the source region and the drain region through the contact hole, 
 wherein a selective etching ratio of the first interlayer insulating film to the crystalline semiconductor layer is from 12 to 15. 
 
   
   
     38. A method for manufacturing a semiconductor device according to  claim 37 , wherein the first interlayer insulating film contains silicon oxide. 
   
   
     39. A method for manufacturing a semiconductor device according to  claim 37 , wherein the source region or the drain region has a thickness from 10 to 50 nm. 
   
   
     40. A method for manufacturing a semiconductor device according to  claim 37 , further comprising a step of fonning a pixel electrode electrically connected to the wiring. 
   
   
     41. A method for manufacturing a semiconductor device according to  claim 37 , wherein the semiconductor device is at least one selected from the group consisting of a personal computer, a video camera, a digital camera, a mobile computer, a player that uses a recording medium, a portable telephone, and an electronic book. 
   
   
     42. A method for manufacturing a semiconductor device according to  claim 37 , wherein a diameter of the contact hole is 1 μm or less. 
   
   
     43. A method for manufacturing a semiconductor device according to  claim 37 , wherein an etching amount of the at least one of the source region and the drain region is less than 5 nm.